Students can use the Spectrum Math Grade 8 Answer Key Chapter 4 Lesson 4.9 Graphing Functions as a quick guide to resolve any of their doubts.
Spectrum Math Grade 8 Chapter 4 Lesson 4.9 Graphing Functions Answers Key
The slope-intercept form of a linear function, y = mx + b, can be used to create a graph of that function.
y = x – 7
Step 1: Mark the point where the line will cross the y-axis (b = -7).
Step 2: From the point which crosses the y-axis, use the slope (m) to find other points on both sides. Remember that slope is found by 
.
Step 3: Draw a line that goes directly through the points found.
Sketch each linear function shown.
Question 1.
a.
y = -3x + 4
Answer:
Explanation:
for x= 0
y = -3x + 4
y = -3(0) + 4
y = 4
Mark the point where the line will cross the y-axis (b = 4).
Draw a line that goes directly through the points found.
b.
y = \(\frac{1}{6}\)x
Answer:
Explanation:
for x= 0
y = \(\frac{1}{6}\)x
y = \(\frac{1}{6}\)(0)
y = 0
Mark the point where the line will cross the y-axis (b = 0).
Draw a line that goes directly through the points found.
Question 2.
a. y = 3x – 1
Answer:
Explanation:
for x= 0
y = 3x – 1
y = 3(0) – 1
y = -1
Mark the point where the line will cross the y-axis (b = -1).
Draw a line that goes directly through the points found.
b. y = 2x + 2
Answer:
Explanation:
for x= 0
y = 2x + 2
y = 2(0) + 2
y = 2
Mark the point where the line will cross the y-axis (b = 2).
Draw a line that goes directly through the points found.
Sketch each linear function shown.
Question 1.
a.
y = 2x – 1
Answer:
Explanation:
for x= 0
y = 2x – 1
y = 2(0) – 1
y = -1
Mark the point where the line will cross the y-axis (b = -1).
Draw a line that goes directly through the points found.
b. y = –\(\frac{1}{2}\)x – 3
Answer:
Explanation:
for x= 0
y = –\(\frac{1}{2}\)x – 3
y = –\(\frac{1}{2}\)(0) – 3
y = -3
Mark the point where the line will cross the y-axis (b = -3).
Draw a line that goes directly through the points found.
Question 2.
a. y = 3x – 6
Answer:
Explanation:
for x= 0
y = 3x – 6
y = 3(0) – 6
y = -6
Mark the point where the line will cross the y-axis (b = -6).
Draw a line that goes directly through the points found.
b. y = –\(\frac{2}{3}\)x + 4
Answer:
Explanation:
for x= 0
y = –\(\frac{2}{3}\)x + 4
y = –\(\frac{2}{3}\)(0) +4
y = 4
Mark the point where the line will cross the y-axis (b = 4).
Draw a line that goes directly through the points found.
Question 3.
a. y = 4x + 3
Answer:
Explanation:
for x= 0
y = 4x + 3
y = 4(0) + 3
y = 3
Mark the point where the line will cross the y-axis (b = 3).
Draw a line that goes directly through the points found.
b. y = –\(\frac{1}{3}\)x + 2
Answer:
Explanation:
for x= 0
y = –\(\frac{1}{3}\)x + 2
y = –\(\frac{1}{3}\)(0) + 2
y = 2
Mark the point where the line will cross the y-axis (b = 2).
Draw a line that goes directly through the points found.
Sketch each linear function shown.
Question 1.
a. y = 3x + 9
Answer:
Explanation:
for x= 0
y = 3x + 9
y = 3(0) + 9
y = 9
Mark the point where the line will cross the y-axis (b = 9).
Draw a line that goes directly through the points found.
b. y = 2x – 5
Answer:
Explanation:
for x= 0
y = 2x – 5
y = 2(0) – 5
y = -5
Mark the point where the line will cross the y-axis (b = -5).
Draw a line that goes directly through the points found.
Question 2.
a.
y = -3x + 4
Answer:
Explanation:
for x= 0
y = -3x + 4
y = -3(0) + 4
y = 4
Mark the point where the line will cross the y-axis (b = 4).
Draw a line that goes directly through the points found.
b.
y = 5
Answer:
Explanation:
for x= 0
y = 5
Mark the point where the line will cross the y-axis (b = 5).
Draw a line that goes directly through the points found.
Question 3.
a. y = \(\frac{1}{2}\)x + 4
Answer:
Explanation:
for x= 0
y = \(\frac{1}{2}\)x + 4
y = \(\frac{1}{2}\)(0) + 4
y = 4
Mark the point where the line will cross the y-axis (b = 4).
Draw a line that goes directly through the points found.
b. y = –\(\frac{4}{5}\)x + 1
Answer:
Explanation:
for x= 0
y = –\(\frac{4}{5}\)x + 1
y = –\(\frac{4}{5}\)(0) + 1
y = 1
Mark the point where the line will cross the y-axis (b = 1).
Draw a line that goes directly through the points found.